In recent years, there developed are various kinds of optical disks each of which is different in the recording density, a cover-layer thickness or the like; for example there are a CD (compact disc) whose usable wavelength is in the vicinity of 780 nm, a DVD (digital versatile disc) whose usable wavelength is in the vicinity of 660 nm, a BD (Blu-ray disc) and an HD-DVD (high definition DVD) whose usable wavelength is in the vicinity of 405 nm, and the like. In such an optical disk apparatus adapted to a plurality of kinds of optical disks whose usable wavelengths are different to one another, there is an apparatus which includes a plurality of objective lenses so as to obtain a focusing spot corresponding to each of the optical disks. (For example, refer to Patent Document 1.)    [Patent Document 1] Japanese Laid-Open Patent Publication No. 2003-281758 (Pages 1 through 11, FIG. 2 through FIG. 13)